Collecting trash

Researchers and fishing crews have found a lot of trash floating in the world's oceans over the past few decades. That trash has even shown up in the remote Arctic Ocean. Now a study shows there is also trash deep down on the Arctic seafloor. Though few people live nearby, researchers found plastic bags, shards of glass and fishing nets. And the litter problem is getting worse.

"Many studies look at litter on the sea surface. We wanted to look at the deep seafloor, " says Melanie Bergmann. She’s a deep-sea biologist with the Alfred Wegener Institute in Bremerhaven, Germany. Bergmann and her colleagues also wondered how that ocean trash might be changing over time. "We wanted to know if it's getting worse, " she says.

And the short answer: Yes!

Each year from 2002 to 2014, Bergmann and her team took pictures of the seafloor at two places in the Fram Strait. This is a narrow stretch of the Arctic Ocean between Greenland and Svalbard, a Norwegian island group in the far North. The researchers lowered cameras down to 2, 500 meters (about 1.5 miles), then towed them behind their research boat. Those cameras snapped photos every 30 seconds.

To date, the scientists have taken 7, 058 photos. Those pictures turned up 89 pieces of litter.

That may not seem like a lot. But it’s about the same concentration of deep-sea trash found far to the south, off the coast of Portugal. This surprised the scientists because there are far fewer people living in the Arctic than in Portugal. Without so many fewer people to litter, they had expected to see little trash on the Arctic floor.

There are also worrying signs that the trash there is growing. At one location, Bergmann’s group found 20 times more litter in 2014 than 10 years earlier.

Where did the trash come from?

Bergmann suspects that the bits of glass they saw came from boats. A warming climate is melting sea ice in the far North. That means it’s easier for ships carrying goods or people to find a clear path. And indeed, shipping traffic there has been increasing.

People on those boats are probably dumping their garbage in the water, either on purpose or accidentally, Bergmann thinks. Because glass is denser than water, it quickly sinks to the bottom. So do dense pieces of plastic.

Lighter bits of plastic travel to the Fram Strait on ocean currents from the South. These currents carry water northward from the coastlines of countries such as the United Kingdom, the Netherlands and Germany. Light-weight plastic floats at first. Over time, however, “algae and other critters grow on it, ” Bergmann notes. Eventually, they weigh the plastic down until it sinks.